It is sometimes necessary and desirable to lock equipment such as heavy electrical switch gear, machine valving, etc. in such a way that access is provided only when several people are present. This is achieved by giving each person a padlock and key which is different from those given to the other persons so that to gain access, everyone must be present to remove the padlocks. Structures which achieve this are taught in U.S. Pat. Nos. 2,560,624 and 3,667,259. The structures in these patents are similar in that they both operate using a scissor arrangement. Two parts are pivoted to one another and when they are in an open position, the device can be applied to a staple associated with a hasp, then closed, and the device is ready to receive padlocks.
There are several disadvantages to the structures shown in these prior art patents. First of all, the strength is entirely dependent on the pin used to pivot the parts to one another. Secondly, because the parts are simply overlapped one over another, it is not difficult to deform the parts and gain unauthorized access. Some attempt has been made in Patent 3,667,259 to overcome this problem by the inclusion of interlocking tabs but nevertheless the difficulty remains.
It is therefore an object of the present invention to overcome the limitations of the prior art devices and to provide an improved device for use in restricting access using a plurality of padlocks.